The revolution will be modular, Zhang insists. Mini Sky City was assembled from thousands of factory-made steel modules, slotted together like Meccano.

It's a method he says is not only fast, but also safe and cheap.

Now he wants to drop the "Mini" and use the same technique to build the world's tallest skyscraper, Sky City.

While the current record holder, the 828m-high Burj Khalifa in Dubai, took five years to "top out", Zhang says his proposed 220-storey "vertical city" will take only seven months -- four for the foundations, and three for the tower itself.

You may have previously read about the Citicorp Center. Joe Morgenstern wrote about the Manhattan skyscraper in a classic New Yorker piece from 1995. The building was built incorrectly and might have blown over in a stiff wind if not for a timely intervention on the part of a mystery architecture student and the head structural engineer on the project.

Tells about designer William J. LeMessurier, who was structural consultant to the architect Hugh Stubbins, Jr. They set their 59-story tower on four massive nine-story-high stilts and used an unusual, chevron-shaped system of wind braces. LeMessurier had established the strength of those braces in perpendicular winds. Now, in the spirit of intellectual play, in his Harvard class, he wanted to see if they were just as strong in winds hitting from 45 degrees. He discovered the design flaw and during wind tunnel tests in Ontario learned the weakest joint was at the building's 30th floor.

The whole piece is here and well worth a read. Last month, the excellent 99% Invisible did a radio show about Citicorp Center and added a new bit of information to the story: the identity of the mystery student who prodded LeMessurier to think more deeply about the structural integrity of his building. (via @bdeskin, who apparently factchecked Morgenstern's piece back in the day)

That's the iconic "Lunch atop a Skyscraper" photo taken in 1932 during the construction of the RCA Building (aka 30 Rock) in NYC. Eleven construction workers eating lunch on a steel girder 840 feet in the air. The shot was a PR stunt to drum up excitement around the near completion of the new skyscraper...no one even knows for sure who took the photo because it was likely a multiple photographer situation. On the same day the lunch photo was taken, some of the same men were photographed taking a nap on the same girder:

Nobody knows how tall Burj Dubai is going to be when completed later this year, only that it will be the world's tallest building by a comfortable margin. Of the mystery height, the builder has only this to say:

If you put the Empire State Building on top of the Sears Tower then it's reasonable to say you'll be in the neighbourhood.

The Metropolitan Life Tower is located on the east side of Madison Square Park at 1 Madison Avenue. It has quietly become one of my favorite buildings in the city; I find myself peering up at it whenever I'm in the area. (I took a photo of the building while in line at the Shake Shack last spring...it's a lovely color in the late afternoon light.) Inspired by a photo posted recently to Shorpy that shows the tower under construction -- and before the addition of the building's iconic clock -- I did some research and discovered three things.

Two. The NY Times ran a story in December 1907 about the eventual completion of the structure and how it would take over as the world's tallest building, surpassing another then-unfinished building, the Singer Tower. In the era before widely available air travel, the building's vantage point was remarkable.

The view from the top was of a new New York. No other skyscrapers obstructed the vista in either direction. Passing the green roof of the Flatiron Building, the gaze literally spanned the Jersey City Heights and rested on Newark and towns on the Orange Mountains, fifteen miles away.

To the southward the skyscrapers bulked like a range of hills in steel and mortar, the Singer tower rising in the midst, a solitary watch tower on a peak. This hid the harbor, but to the left beyond the bridges, reduced at this height to gray cobwebs, the eye caught the sunlight on the sea -- a long strip of shimmering silver beyond Coney Island and the Rockaways.

When you read up on Hong Kong prior to visiting, most guides make mention of the different levels of the city. Physical levels, that is.[1] The city proper is built on a hill and there are so many tall buildings that you quickly lose interest in counting all of them; imagine Nob Hill in San Francisco, except with skyscrapers. The famous escalator cuts through the city up the hill; the change in elevation over its short span is impressive, especially when you get to the top and realize you're actually only a few horizontal blocks from where you started.

Much of the HK's retail and dining is vertically oriented; there's just not enough storefront real estate to contain it all. You'll typically find restaurants on the 3rd or 4th floor of buildings and 3- to 6-level malls jammed with retail stores are everywhere; the Muji we went to was on level 7 of Langham Place. Skyways connect buildings together -- as do subways -- so much of the foot traffic in some areas isn't even on the street level. Cars and buses (with two levels) zoom on highways passing over city streets and other highways, past the midlevels of buildings just a block or two away and down the hill. As a pedestrian, you can find yourself staring up at a 50-story building in front of you and then turning slightly to peer into the 15th floor of a building 2-3 blocks away. It's a disorienting sensation, being on the ground level and the 15th floor at the same time, as if the fabric of space had folded back onto itself. Many people aren't used to negotiating cities so intensively 3-D, particularly when all the maps reinforce the Flatlandness of the city grid.

[1] Well, not entirely physical. There are economic levels for one; the woman selling eggs on the street for a couple of HK$ each while tourists shop for Prada and Burberry only blocks away. You've got British culture over Chinese culture...and then Chinese culture layering back over that since the handover in 1997. You've got different levels of authenticity, from the fake electronics & handbags to the real Chanel cosmetics & Swarovski crystal, from the more touristy, mediated experiences to the hidden corners of real Hong Kong.